Over the years, fringe scientists have claimed that there are several compounds in everyday foods that can help prevent cancer.
From phytochemicals found in fruits to omega-3s found in nuts, popular ideas about cancer-fighting foods have come and gone.
Now, the focus seems to be on an unlikely vegetable: fungus.
An intriguing tweet posted by nutrition coach Lori Shemek shared details of a study involving nearly 20,000 people that appeared to suggest that eating just one mushroom per day could reduce the risk of developing all types of cancer by almost half.
‘Cancer Absolutely hates mushrooms,” wrote Shemek, who is not a doctor.
The claim seems far-fetched, but recent studies seem to suggest that some types of edible mushrooms could be useful in fighting cancer cells. So should we increase our mushroom content?
Shiitake and turkey tail mushrooms are commonly touted for their potential to prevent cancer. Neither has been proven effective by scientists or American authorities.
About 20 million cases of cancer were diagnosed in 2022, but that number is expected to increase to more than 35 million cases by 2050, according to the American Cancer Society.
Asian doctors have used mushrooms for centuries in hopes of treating a number of health problems. Currently, turkey tail mushroom and shiitake mushroom extracts are approved to treat cancer in Japan and China.
American doctors became accustomed to this trend in the early 21st century, while a number of studies have put vegetables in the spotlight in recent years.
One is the 2021 review that nutrition coach Lori Shemek refers to, conducted by experts at Pennsylvania State University.
Scientists reviewed 19 previous studies of many varieties of mushrooms and found that eating 18 grams of any mushroom a day could reduce the risk of developing all types of cancer by 45 percent.
That’s about one standard-sized white button mushroom a day.
However, of the 19 studies they analyzed, only 11 controlled for other factors that could have influenced cancer risk, such as exercise, body weight or other dietary choices.
And those who eat mushroom-rich diets are also likely to eat other vegetables and fruits, in addition to exercising, meaning their low cancer risk may come from other elements of their lifestyle.
Of the 270 potentially useful mushrooms, only 32 have shown scientific benefits in the laboratory, most of the evidence shows.
And of those 32, only 11 have been tested on people, according to a review 2022 of Indian and Belgian scientists.
This review concluded that five types of mushrooms are the most promising: shiitake, turkey tail, reishi, white cap, and maitake.
It is believed that the vitamins and antioxidants found in these five mushrooms could help protect against cancer by silencing the effect of free radicals, molecules that damage our DNA and our cells.
These include vitamins B, D, selenium and niacin, as well as two little-known compounds called ergothioneine and lentinan.
For example, a 2011 study suggested that taking reishi extract for a year could reduce people’s risk of developing colon cancer.
The researchers did this by studying 225 Japanese people with abnormal cells in their colon, called polyps. Polyps are abnormal cells that develop into cancerous tumors in about 10 percent of cases.
At the end of the year, people who took reishi extract had fewer polyps overall than people who did not.
This suggested that the extract could help prevent colon cancer, according to the US. National Cancer Institute wrote.
However, it was done on a small group of people and has not been tested in this way again. It’s also unclear whether the researchers controlled for other factors that could have influenced their polyps, such as genetics, diet or exercise routines.
Evidence on reishi in general is sparse, which explains why no U.S. regulatory agency has approved the mushroom as a treatment or prevention of any medical condition, according to the NCI.
Much of the interest in the turkey tail mushroom is due to the effects of a compound that may be distilled from the fungus called polysaccharide K (PSK).
Japanese scientists suggest that PSK could help the body produce more proteins that fight harmful invaders such as viruses or cancer.
When taken along with other treatments, such as surgery or chemotherapy, people who took PSK supplements in about 20 different studies were less likely to have recurrent stomach, colorectal, and lung cancers than those who took traditional treatments alone. according to the NCI.
But these studies only included small groups of people, were conducted primarily in Asia, showed minimal benefit, and most did not control for other potentially beneficial influences.
In all, this study and others have not provided overwhelming evidence that mushrooms can treat or protect against cancer, said Dr. Liz O’Riordan, a breast cancer surgeon. told the Irish examiner.
‘What we do know is that being at a healthy weight and exercising can reduce the risk of most common cancers by half. However, there is no evidence to suggest that mushrooms reduce the risk or that eating soy reduces the risk of getting cancer,” said Dr. O’Riordan.
It’s always good to eat a more nutritious diet, but mushrooms are unlikely, based on current evidence, to be a magic bullet, he suggested.
So adding mushrooms to your diet if you’re interested in getting more nutrients isn’t a bad idea, but US authorities warn against relying on it.
“Patients will read these blogs and podcasts, spend money on supplements and avoid sugar, or buy turkey tail mushrooms in the belief that a person has said it will cure them or reduce their risk,” Dr. O’Riordan said, ” and not one supports science.’
